feat: add dark theme support and update homepage content

- Integrated next-themes for dark mode theming with default dark theme
- Added new UI components (GridBlink, Spotlight) and enhanced world map with cyan glow effects
- Updated homepage messaging to emphasize Mycelium as a living network with new audience imagery

src/styles/tailwind.css

@@ -221,3 +221,10 @@
     @apply bg-background text-foreground;
   }
 }
+
+.blink-square.active {
+  fill: #79f4ff;
+  opacity: 0.15;
+  filter: drop-shadow(0 0 6px #90f6ff);
+  transition: opacity 1s ease-out;
+}